The invention relates to the use of an object instrumented by motion sensors and used to convert movements of a user carrying the object into movements of a point in a plane. These objects can thus be designated generically by the term “pointers”. The user normally holds the pointer in his hand, although other modes of carriage may easily be envisaged depending on the applications, such as fixing to the head or one of the limbs of the carrier.
They may have diverse functions, notably: remote control of an audiovisual apparatus (television, reader/recorder of disks, hi-fi system), where the point is a program or a function to be chosen from a menu; remote control of a household apparatus where the pointer designates the apparatus and has it execute a function; computer remote control where the pointer is programmed as a function of the applications executed by the computer; electronic games interface where, depending on the game, the pointer may be an object manipulated by the user (golf club, tennis racket, bowling ball, handgun, hip gun or rifle, etc.); assistance for the man-machine interface or remote control intended for persons with reduced mobility (for example, fixing of a pointer to the head, the spectacles, an earpiece, or any other part tied to the movements of the head, so as to aid persons with motion deficiency or who are unable to use a conventional hand-held mouse to direct a pointer at the screen). In general, the pointer is equipped with buttons which allow selection of a command, which can be programmed to execute a function (or a service) or to associate a different pointer state during the pointing gesture (trajectory with button pressed vs trajectory with button released, thereby making it possible for example to take as information not the situation of a point on the screen but a cursor trajectory that may itself be associated with an action, etc.). The movements of the pointer in space comprise rotations and translations. They can be measured by sensors of various types: image sensors can measure rotations and translations at one and the same time by comparison of successive images and geometric transformations; a magnetometer, an accelerometer or a single-axis gyrometer can measure a rotation about said axis; a combination of magnetometers, accelerometers and/or of gyrometers can measure the translations and rotations about several axes; a combination of sensors of the previous types improve measurement accuracy, redundancy allowing determination of confidence intervals; the combination can comprise one or more cameras and several magnetometric, accelerometric and/or gyrometric sensors. Another rotation sensor, insensitive to accelerations, may be a brightness sensor. If it is a photoelectric cell, it is known that the amount of light received by said cell is proportional to its light receiving area and to the cosine of the angle of inclination of the rays with its normal. The light source may be the sun, or some other quasi-pointlike source, bulb type, situated far enough away for its emission rays to be considered parallel to one another over the whole of the volume of the gestural experience. To avoid problems of changeable ambient brightness, it is advantageously possible to use a “fly's eye” multi-facet type sensor, the angular direction of reception being the facet which measures the highest luminous flux.